In recent years, mobile devices with QWERTY keypads have become popular in the wireless industry. Mobile devices with QWERTY keypads are convenient for operators because the operator can usually enter in text or other symbols without having to cycle through various settings, which is not the case for devices with keypads containing the standard 3 column by 4 row grid. The current trend with mobile devices, however, is to shrink the overall size of the devices. Given the limited amount of available space on a mobile device, it can be difficult to accommodate QWERTY keypads.
Some QWERTY keypads may contain up to thirty-five keys. Each key typically sits over a dome or popple, which is a switch that is positioned on a circuit board and that typically provides tactile feedback to the operator. When a key is pressed, the key contacts the dome and causes it to collapse. When this event occurs, a circuit underneath the dome is completed, and a corresponding event can be executed on the mobile device. Because each key in a QWERTY keypad has a corresponding dome, a mobile device containing this type of keypad may include up to thirty-five domes, as well.
Due to the spatial constraints of mobile devices, some of the domes in a mobile device that includes a QWERTY keypad may be placed close to the edge of the device's circuit board. By positioning the domes near the edges of the circuit board, however, it may be easier for external contaminants, such as dust or water, to enter the mobile device due to the construction of the keypad. Although it is possible to move the domes that are located on the edges of the circuit board slightly towards the center of the board, such a process can cause the domes to be misaligned with the keys on the edges of the keypad. This misalignment can degrade the tactile feedback performance of the mobile device.